Spinal Dural Arteriovenous Fistula: A Cinical Fetures Study
*Kumara Tini. ** Shakir Husain
* Neurology Departement-Faculty of Medicine, Udayana University Denpasar-Bali Indonesia ** Director of Interventional Neurology and Stroke Program Saket City Hospital-New Delhi Abstract
Background
Despite being the most commonly encountered spinal vascular malformation (~70%), spinal dural arteriovenous fistulas (SDAVFs) are still underdiagnosed entities and accounted for nearly one third unexplained myelopathy (1,2). If not treated properly can lead to considerable morbidity with progressive spinal cord symptom. SDAVFs present a diverse and often misleading clinical presentation. As this condition can result in permanent spinal cord injury, all patient required treatment. Failure to recognize and treat SDAVF in timely fashion can result in irreversible neurologic disability(2,3).
Material and method
We reviewed 19 patients of SDAVF from 2009 to 2013. The collected data were analysed to study the epidemiology, clinical pictures and courses, imaging findings , spinal angiogram , endovascular treatment and its response to the treatment. This study is aimed to provide better understanding of this disease.
Result
Among 19 patients, 84.2% were male and 15% were female. Their mean age of onset was 57.2 years (ranging from 29.5-73.8) with mean age on diagnosis was 58.57 years (ranging from 31-74). The delay in the diagnosis was 22.6 months (ranging from 0.3-108). Majority of the patients were in the sixth decade (52.6%). Initial motoric and sensoric symptoms presenting as intermittent claudication of lower legs, radicular pain and perineal numbness while symptoms upon presentation were mixed type UMN-LMN paraparesis , lower limb hypo-aesthesia and bowel-bladder dysfunction. Most of the patient showed imajing abnormalities on Spinal MRI ( perimedullary flow voids, T2 spinal cord hyperintensity and cord swelling). All patient received endovascular embolization and 23% of those showed immediate improvement after procedure.
Conclusion
Although rare, as spinal DAVF is difficult to be diagnosed and would have poor outcome by the time definitive diagnosis made. The delay in diagnosis could be minimized by more understanding about this disease epidemiology, cliniical features and imaging findings. It should be considered in differential diagnosis of selected patients, such as older patient (particularly men) with progressive myelopathy. The prompt treatment by endovascular embolization may benefit patient if performed early.
Keyword:
Background
Despite being the most commonly encountered spinal vascular malformation (~70%), spinal dural
arteriovenous fistulas (SDAVFs) are rare and still underdiagnosed entities, which if not treated properly can lead to considerable morbidity with progressive spinal cord symptom (1,2). Up to the present day physician continue to be perplexed by the extensive changes in structure and function caused by the development of an abnormal but often tiny connection between a radicular artery and radicular vein, at some level of the spinal axis (3). SDAVF present a diverse and often misleading clinical presentation. As this condition can result in permanent spinal cord injury, all patient required
treatment. Failure to recognize and treat SDAVF in timely fashion can result in irreversible neurologic disability (4).
We reviewed 19 patient of SDAVF from 2009 to 2013. The collected data were analysed to study the epidemiology, clinical picture and course, imaging findings , spinal angiogram , endovascular treatment and its response to the treatment. This study is aimed to provide better understanding of
this disease.
Materials and methods
The clinical records of all patients, angiographically diagnosed with SDAVFs for which endovascular embolization was done as the primary treatment modality at our institution between december 2009 and april 2013 were retrospectively reviewed. The data was analysed on the epidemiology, clinical history and course of the disease, MRI finding, site of SDAVF angiographycally, and
immediate response to endovacular treatment.
Results
Of the 19 patients, 84.2% were male and 15.8% were female. Their mean age of onset was 57.2 years (range 29.5-73.8) with mean age of diagnosis was 58.57 years (range 31-74). One patient is under age of 30 at the onset and majority of the patient were in their sixth decade (10 patients, 52.6%).
Clinical features
Motor weakness was the most common initial symptom either at onset (52.6%) or at time of
diagnosis (89.5%). Root pain presenting as radicular pain in one or both legs was the most common sensory symptom at onset, 45.5% of these associated with low back pain. At the time of diagnosis majority of the patient came with motoric deficit and micturition disorder, while sensory deficit become the most common feature of sensory symptom.
Leg weakness initially manifested as a transient on and off leg weakness with intermittent
claudication in 8 patients (42 % ) and as the disease progressed they become permanent, most of them experienced gradually worsening of leg weakness (94.7%) only 1 patient developed sudden onset of paraparesis.
symptom and associated with low back pain in 45.5 % patient, while paresthesia on both feet were reported in 36.6% of sensory symptom.
At the time of diagnosis the most common symptom were leg weakness (89.5 %), micturion difficulties (84.2 %) and sensory disturbance presented as numbness in 63.1 % of patient, involved
mostly on hip down and gluteal area. Thirteen patients ( 68 %) presented with complete motor, sensory and autonomic disturbances. In general 68% of the patient had mild paraparesis ( motoric power of 4) , 50 % of them need support while walking. Three patient (20 %) were wheelchair bound.
Upon neurological examination , 53.5% presenting upper motor neuron involvement ( hyperreflexia,
clonus, spasticity of lower limbs and Babinsky sign) , 46 % presenting Lower motor involement ( hypotonus and absent of ankle reflex) . Patient with sensory deficit, segmental sensory deficit was the most common feature only 2 patient showed perineal sensory deficit.
Diagnosis
The delay in the diagnosis was 22.6 months (range 0.3-108), 53% of patient came to our institution after 1 year of onset, one patient came 15 days after the onset and one patient after being a bed
ridden for 9 years. MRI were performed in 11 patients. All of the MRIs showed abnormal imaging finding. Cord edema was seen in 5 MRI (45.5%), Hyperintensiity was present in 10 MRIs (90%) and all of MRIs showed perimedulary flow voids. Most of the lesion were located at Dorsal level (54.5%), Dorsolumbal lesion in 36.4% of MRI, Lumbosacral lesion in 18.2% of MRI and no Cervical lesion was found.
Result of spinal Angiogram showed spinal Dural arteriovenous fistula (spinal DAVF) at upper dorsal in
15.8% angiogram, lower dorsal in 63.2% of angiogram and lumbar region in 21% of angiogram. Right and left fistula equally involved, and 2 patients (10.5%) had both sides fistula.
Endovascular treatment
All of 19 patient were treated by endovascular arteriovenous fistula embolization . PVA were used in 44.4% patient and Glue ( NBCA) in 55.5% patient. Complete obliteration were achieved in almost all of the cases, and only 2 cases did not achieved complete embolization due to anastomosis with
other segmental artery . No complication were found due to endovascular embolization. Immediate response the next day after the embolization were found in 5 patient (23.3%).
Disscusion Epidemiology
Patient affected by spinal DAVF are mostly middle-aged men (1,2), as showed as well in this study 84.2% were male with age of onset 57.2 years. Patient under age of 30 are rarely reported, which
is the most common region affected by trauma as this is the most mobile part of spinal collum, but cervical spinal DAVF only consists of 6% spinal DAVF combined with sacral region.
Clinical presentation
At the onset of disease, initial symptom are often non-specific. They include gait difficulties, symmetrical or asymmetrical sensory symptom as reported in this series commonly experinced as positive symptom such as paresthesia and radicular pain. Disturbance of micturiton and defecation may occur at the start but most often developed in later phases of disease (3,4).
Intermittent Claudication during activity and transient weakness of both leg occured in 42% of patient. Reduced arteriovenous gradient result in decrease in tissue perfusion and venous infarction.
An increase in arterial pressure during activity leads to an increase in venous pressure, this explained patient report that symptom during activity. The lower thoracic region has relatively fewer venous outflow channel at segmental level than cervical and lumbosacral region. The differences in segmental outflow probably contribute to the phenomenone that venous congestion is transmitted in a caudo-cranial direction through out the spinal cord and the first symptoms of myelopathy tend to reflect dysfunction of the lowest part of the cord, that is conus medularis. This explained the inital motoric and sensoric symtopm presenting as lower leg weakness, radicular pain and some perineal
numbness (4,5).
As the disease progess , involvement of more cranial spinal cord develop and at the later phase presented with upper motor neuron features of paraparesis, segmental sensory deficit and micturition and defecation disturbance (4,5).
Diagnosis
Spinal DAVF is hard to diagnose, because of the misleading nature of the initial symptoms and rarity
of the disease (1,2). In early phase as report in this series, this disease may resemble polyneuropathy, but involvement of arms is rare in spinal DAVF except cervical spinal DAVF. Spinal DAVF begin distally and extend more proximal , ultimately to buttock which is exceptionaly uncommon in polyneuropathy. Asymmetrical motor and sensory deficits are common in spinal DAVF , where as
polyneuropathy presenting symmetrical symptom and sign.
Although the arrival of MR imaging and selective angiography significantly improves the ability to characterize the spinal DAVFs, these lesion remain inefficiently diagnosed. The time between the onset of symptoms and diagnosis was 22.6 months. This delay in diagnosis likely ( in part) due to non-specific clinical presentation. The rarerity of the spinal DAVF commonly makes the physician to consider many other disorder before considering spinal DAVF, eventhough as showed in this study
all of the spinal DAVF MRI showed perimedullary flow voids and hypertensity of spinal cord (4,5).
Majority occured in dorsal and lumbar region with none occured in cervical, where as AVM occur much more in the cervical region (3,4).
Standart catheter angiography remains the gold standart in the diagnosis of spinal DAVFs. This study showed most common sites of the fistula was lower dorsal and lumbar region and there was no left
or right side preference . It occured mostly only on one side, bilateral fistula were found in 2 patient (10%).
Endovascular treatment
Over the last several decade, improvement in endovascular technique and embolic agents have greatly improved the ability to definitively treat majority of spinal DAVFs. This improvement have
been associated with shorter hospital stays, minimal procedure morbidity, and early initiation of rehabilitation for patient undergoing spinal DAVF embolization. Rate of definitive embolization have ranged between 25 and 100%, depending in part on embolic agent used and the use of variable stifness microcatheter (6). In this study 44.4% of the patient spinal DAVF embolized with PVA and 55.5% with NBCA. Incomplete obliteration occured in 2 patient treated using PVA due to anastomosis of dural fistula with other radiculomedullary artery. Improvement directly a day after embolization were reported in 23.3% of patient, in which walking difficulty were likely to improve
following embolization, whereas micturition and sensory disturbances were less likely to improve. One patient with 15 days onset was fully recovered a day after embolization. This explained that spinal DAVF is a treatable disease if treated early.
Conclusion
Althoug rare, as spinal DAVF is difficult to diagnose it will have poor outcome by the time definitive
diagnosis made. The delay in diagnosis could be minimized by more understanding about this disease epidemiology, cliniical features and imaging findings . The prompt treatment by endovascular embolization may benefit patient if performe early.
References
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3. Lev N, Maimon S, Rappaport ZH et-al. Spinal dural arteriovenous fistulae: a diagnostic challenge. Isr. Med. Assoc. J. 2001;3 (7): 492-6
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